Despite the differences between ethology and behaviorism, the two schools had one thing in common. Both were reactions against the overinterpretation of animal intelligence. They were skeptical of “folk” explanations and dismissed anecdotal reports. Behaviorism was the more vehement in its rejection, saying that behavior is all we have to go by and that internal processes can be safely ignored. There is even a joke about its complete reliance on external cues, in which one behaviorist asks another after lovemaking: “That was great for you. How was it for me?”
In the nineteenth century, it was perfectly acceptable to talk about the mental and emotional lives of animals. Charles Darwin himself had written a whole tome about the parallels between human and animal emotional expressions. But while Darwin was a careful scientist who double-checked his sources and conducted observations of his own, others went overboard, almost as in a contest of who could come up with the wildest claim. When Darwin chose the Canadian-born George Romanes as his protégé and successor, the stage was set for an avalanche of misinformation. About half the animal stories collected by Romanes sound plausible enough, but others are embellished or plainly unlikely. They range from a story about rats forming a supply line to their hole in the wall, carefully handing down stolen eggs with their forepaws, to one about a monkey hit by a hunter’s bullet who smeared his hand with his own blood and held it out to the hunter to make him feel guilty.15
Romanes knew the mental operations required for such behavior, he said, by extrapolating from his own. The weakness of his introspective approach was, of course, its reliance on one-time events and on trust in one’s own private experiences. I have nothing against anecdotes, especially if they have been caught on camera or come from reputable observers who know their animals; but I do view them as a starting point of research, never an end point. For those who disparage anecdotes altogether, it is good to keep in mind that almost all interesting work on animal behavior has begun with a description of a striking or puzzling event. Anecdotes hint at what is possible and challenge our thinking.
But we cannot exclude that the event was a fluke, never to be repeated again, or that some decisive aspect went unnoticed. The observer may also unconsciously have filled in missing details based on his or her assumptions. These issues are not easily resolved by collecting more anecdotes. “The plural of anecdote is not data,” as the saying goes. It is ironic, therefore, that when it was his own turn to find a protégé and successor, Romanes chose Lloyd Morgan, who put an end to all this unrestrained speculation. Morgan, a British psychologist, formulated in 1894 the probably most quoted recommendation in all of psychology:
In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower on the psychological scale.16
Generations of psychologists have dutifully repeated Morgan’s Canon, taking it to mean that it is safe to assume that animals are stimulus-response machines. But Morgan never meant it that way. In fact, he rightly added, “But surely the simplicity of an explanation is no necessary criterion of its truth.”17 Here he was reacting against the mindset according to which animals are blind automata without souls. No self-respecting scientist would talk of “souls,” but to deny animals any intelligence and consciousness came close enough. Taken aback by these views, Morgan added a provision to his canon according to which there is nothing wrong with more complex cognitive interpretations if the species in question has already been proven to have high intelligence.18 With animals such as chimpanzees, elephants, and crows, for which we have ample evidence of complex cognition, we really do not need to start at zero every time we are struck by seemingly smart behavior. We don’t need to explain their behavior the way we would that of, say, a rat. And even for the poor underestimated rat, zero is unlikely to be the best starting point.
Morgan’s Canon was seen as a variation on Occam’s razor, according to which science should seek explanations with the smallest number of assumptions. This is a noble goal indeed, but what if a minimalist cognitive explanation asks us to believe in miracles? Evolutionarily speaking, it would be a true miracle if we had the fancy cognition that we believe we have while our fellow animals had none of it. The pursuit of cognitive parsimony often conflicts with evolutionary parsimony.19 No biologist is willing to go this far: we believe in gradual modification. We don’t like to propose gaps between related species without at least coming up with an explanation. How did our species become rational and conscious if the rest of the natural world lacks any stepping-stones? Rigorously applied to animals—and to animals alone!—Morgan’s Canon promotes a saltationist view that leaves the human mind dangling in empty evolutionary space. It is to the credit of Morgan himself that he recognized the limitations of his canon and urged us not to confuse simplicity with reality.
It is less known that ethology, too, arose amid skepticism about subjective methods. Tinbergen and other Dutch ethologists were shaped by the hugely popular illustrated books of two schoolmasters who taught love and respect for nature while insisting that the only way to truly understand animals was to watch them outdoors. This inspired a massive youth movement in Holland, with field excursions every Sunday, that laid the groundwork for a generation of eager naturalists. This approach did not combine well, however, with the Dutch tradition of “animal psychology,” the dominant figure of which was Johan Bierens de Haan. Internationally famous, erudite, and professorial, Bierens de Haan must have looked rather out of place as an occasional guest at Tinbergen’s field site in the Hulshorst, a dune area in the middle of the country. While the younger generation ran around in shorts holding butterfly nets, the older professor came in suit and tie. These visits attest to the cordiality between both scientists before they grew apart, but young Tinbergen soon began to challenge the tenets of animal psychology, such as its reliance on introspection. Increasingly, he put distance between his own thinking and Bierens de Haan’s subjectivism.20 Not being from the same country, Lorenz showed less patience with the old man, whom he—in a play on his name—mischievously dubbed Der Bierhahn (German for “the beertap”).
Tinbergen is nowadays best known for his Four Whys: four different yet complementary questions that we ask about behavior. But none of them explicitly mentions intelligence or cognition.21 That ethology avoided any mention of internal states was perhaps essential for a budding empirical science. As a consequence, ethology temporarily closed the book on cognition and focused instead on the survival value of behavior. In doing so, it planted the seeds of sociobiology, evolutionary psychology, and behavioral ecology. This focus also offered a convenient way around cognition. As soon as questions about intelligence or emotions came up, ethologists would quickly rephrase them in functional terms. For example, if one bonobo reacted to the screams of another by rushing over for a tight embrace, classical ethologists will first of all wonder about the function of such behavior. They’d have debates about who benefited the most, the performer or the recipient, without asking what bonobos understood about one another’s situations, or why the emotions of one should affect those of another. Might apes be empathic? Do bonobos evaluate one another’s needs? This kind of cognitive query made (and still makes) many ethologists uncomfortable.